Which converter should I use to play with old consoles over a modern TV?

If you connect an old console that still has a red, white, yellow cable to a modern TV, the picture is usually very bad. But there are converters for something like that. However I do not know which converter I should buy. Since my TV still has a red, white, yellow connection, I do not know if it makes a difference if I use a 13 euro converter or via this connection: Because here:

RCA to HDMI Adapter | GANA AV to HDMI Converter AV to HDMI Adapter Support 1080P with USB Charging Cable Protective Cover for PC / Nintendo / Xbox / PS4 / PS3 / TV / STB / VHS / VCR / Camera / DVD (Black) https://www.amazon.de/...072N2Q55Y/

Buying a converter here is in my opinion 'thrown out money, the result may be even worse than without it.

Red and white transmit the sound and yellow the picture - an AV-HDMI converter makes sense only if your TV does NOT have a suitable AV input. But your TV has one!